1. Field of the Invention
The present invention is generally related to the shipment of nuclear fuel and particularly to a basket for shipping spent nuclear fuel.
2. General Background
Spent nuclear fuel is commonly stored at a site other than where the fuel was used in a commercial reactor. This requires the use of special shipping containers for the spent fuel. This is also true for spent nuclear fuel from naval vessels. The shipping containers are normally formed from a cask and a basket received in the cask that receives the fuel. The cask is normally required to prevent radiation loss to the surrounding environment, to serve as a heat sink for removing heat generated by the nuclear fuel, and to minimize shock loads transferred to the fuel in the event of an accident during transportation. The shipping basket received in the cask is normally required to act in conjunction with the cask to retain the fuel in the loaded pattern, minimize shock transfer to the fuel, transfer heat to the cask, and provide criticality control. Typically, a cask is heavily shielded. The shipping basket typically utilizes spacing geometry, neutron poisons, and limits the quantity of fuel carried to provide criticality control. This presents a problem of limiting the amount of spent fuel that can be loaded into one shipping basket and cask. This presents a need for a shipping basket that is able to receive a greater volume of spent fuel while still providing criticality control to help reduce the number of shipping baskets and casks required when shipping spent nuclear fuel.